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.. _json_encoding:
JSON Encoding
=============
It is often useful to be able to control how objects are encoded to
and decoded from JSON. Quart makes this possible via a JSONProvider
:class:`~quart.json.provider.JSONProvider`.
Money example
-------------
As an example lets consider a Money object,
.. code-block:: python
class Money:
def __init__(self, amount: Decimal, currency: str) -> None:
self.amount = amount
self.currency = currency
which we desire to translate to JSON as,
.. code-block:: json
{
"amount": "10.00",
"currency": "GBP"
}
using encoders and decoders as so,
.. code-block:: python
from quart.json.provider import _default, DefaultJSONProvider
class MoneyJSONProvider(DefaultJSONProvider):
@staticmethod
def default(object_):
if isinstance(object_, date):
return http_date(object_)
if isinstance(object_, (Decimal, UUID)):
return str(object_)
if is_dataclass(object_):
return asdict(object_)
if hasattr(object_, "__html__"):
return str(object_.__html__())
if isinstance(object_, Money):
return {'amount': object_.amount, 'currency': object_.currency}
raise TypeError(f"Object of type {type(object_).__name__} is not JSON serializable")
@staticmethod
def dict_to_object(dict_):
if 'amount' in dict_ and 'currency' in dict_:
return Money(Decimal(dict_['amount']), dict_['currency'])
else:
return dict_
def loads(self, object_, **kwargs):
return super().loads(object_, object_hook=self.dict_to_object, **kwargs)
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